All publications cited herein are incorporated by reference in their entirety to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
There is a need for wireless, implantable sensors that can detect the concentrations of various proteins, metabolites and ions in blood in real-time. Direct implantation of biosensors within tissue does not facilitate such detection, as it relies on the diffusion of molecules from the blood to the interstitial fluid to the sensor. This diffusion process takes substantial time due to the distance between the blood to the sensor. There is thus a delay of tens of minutes to hours between the variations in concentration of target analytes in the blood and that detected by the sensors. Furthermore, the eventual encapsulation of implanted devices within a thick layer of fibrous tissue due to tissue reaction further impedes the diffusion of such molecules to onboard sensors.
The invention described herein presents a technique for interfacing a sensor chip directly with the vascular system to allow real-time detection of species in blood, through the formation of a capillary bed within the chip. As a result, diffusion of target molecules in blood to the sensors occurs at the same physiological length scale as that from blood in capillaries to the tissue they supply in the body.